In the use of medical electrodes of the type which are adhesively attached to a person's skin for measuring electrical biosignals generated from the person's body, it is common to use a flexible lead wire for connecting the electrode to a recording instrument such as an electrocardiogram machine. The lead wire may consist of multiple metal strands or a bundle of carbon fibers surrounded by an extruded tubular layer of electrical insulating plastic material. It has been found desirable to shield the lead wires to prevent electrostatic or electromagnetic noise in the surrounding area and especially the high noise generated in a hospital from mixing with the biosignals being conducted by the lead wires. The shielding is usually accomplished by a braided metal wire or deposited metal layer which surrounds the tubular layer of electrical insulating material. The braided wire or metal layer is surrounded by another extruded tubular layer of electrical insulating material.
Sometimes it is desirable to take X-rays of a person's body to which is attached a plurality of electrodes which are connected to corresponding lead wires extending to a recording instrument. However, when the shielded lead wires are being used to connect the electrodes to the recording instrument, the metal in the lead wires blocks or is opaque to the passage of X-rays and produces undesirable images on the X-ray film. One proposed solution to this problem has been a combined electrode and lead wire assembly as disclosed in U.S. Pat. No. 4,442,315. In this patent, a generally flat lead wire is formed as an integral part of a generally flat electrode and includes deposited band-like layers of electrically conducting material in the form of a conductive paste and carbon shield layers. However, since the lead wire is made integrally with the electrode, it is necessary to dispose of a lead wire with each electrode. In addition, the lead wire disclosed in this patent cannot be produced on conventional wire manufacturing equipment. Other forms of shielded conductors or wires or cables and commonly used for ignition cables, are disclosed in U.S. Pat. Nos. 3,680,027, 3,683,309, 3,991,397, 4,748,436 and 5,034,719. However, after reading each of the patents, it is apparent none of the shielded cables disclosed in these patents would function effectively as a lead wire for a medical electrode and for also being translucent to X-rays.